San Diego's offense returned to life thanks to new head coach Mike McCoy and Philip Rivers' resurgence under center. The Chargers' 7.5 net yards per pass attempt trailed only Denver's 7.8 for tops in the NFL, and they averaged 270.5 passing yards and two passing touchdowns per game. However, they still need to tighten up a defense that averaged a second-worst 6.1 yards per play, especially in a division where they face Peyton Manning and Jamaal Charles twice each.

Their key move in free agency was locking up Donald Butler to a seven-year, $52-million deal, but they need a space-eater ahead of him and Manti Te'o. Notre Dame's Louis Nix would be perfect for the Chargers. He's a big body at 6-2 and 331 pounds yet moves well for his size. He can knock his blocker back and has a good swim move. An added bonus: drafting Nix would reunite him with Te'o and recreate the heart of Notre Dame's 2012 defense, which carried them to the BCS title game. He did have season-ending meniscus surgery, though.

There aren't too many pure nose tackles beyond Nix that are worth drafting this high, but they could go for another former Notre Dame defensive lineman in Stephon Tuitt. Tuitt has great size at 6-5 and 304 pounds, and that translates to great length (34 3/4-inch arm length) and surprising quickness. He's versatile enough to play his natural position of defensive end or move inside. However, Tuitt had weight issues entering his junior season, and he disappeared on tape at times.

The Chargers also need help in the secondary. The unit allowed 7.1 net yards per attempt, tied with the Falcons and the Redskins for worst in the NFL, and their 258.7 passing yards allowed per game were fourth-worst in the league.

Ohio State cornerback Bradley Roby would inject a dose of athleticism into the Chargers' secondary. Roby ran a 4.39-second 40 at the Combine, has fluid hips and has the physical tools to be a success. However, he did have a few ugly games last season, most notably when he was burned by projected mid-round pick Jared Abbrederis for 207 yards and a score on 10 catches. He also has a history of off-field issues.

TCU's Jason Verrett also would work well here, if he's still available. At 5-9, Verrett doesn't have ideal size, but he more than makes up for it with his aggressive, ball-hawking style of play. He has good technique, knows where the ball is and can get physical with his receiver. It also doesn't hurt that Verrett's 4.38-second 40 makes him just as fast as Roby.

Even with their issues on defense, the Chargers could draft a wide receiver to pair with Keenan Allen. There aren't many big, imposing receivers worth a late-first round pick, but the Chargers could have a few dynamic options available, most notably USC wideout Marqise Lee. Lee, a former long-jumper and sprinter on the Trojans' track team, had a down season in 2013 due to nagging injuries, but his overall body of work is still impressive. He has the speed, athleticism and big-play potential that would complement Keenan Allen's route-running ability.